TMD warns of more rain and flash floods across upper Thailand

The Thai Meteorological Department (TMD) said in its 24-hour weather forecast on Thursday (June 11, 2026) that upper Thailand would see more rain, with heavy rain in some areas and very heavy rain in parts of the upper North, upper Northeast, East and the South’s west coast.

The conditions were caused by a monsoon trough stretching across Myanmar and the upper North into a low-pressure area over the upper South China Sea, while a moderate southwest monsoon continued to cover the Andaman Sea, Thailand and the Gulf of Thailand.

People in those areas were advised to prepare for heavy to very heavy rain and accumulated rainfall, which could trigger flash floods and runoff, especially in risk areas near waterways and in low-lying zones.

Wind and waves in the upper Andaman Sea were moderate, with waves around 2 metres high.

In the lower Andaman Sea and the Gulf of Thailand, waves were 1–2 metres high, rising above 2 metres in thunderstorm areas.

Boats in the Andaman Sea and the Gulf of Thailand were advised to proceed with caution and avoid sailing in thunderstorm areas.

Weather forecast for Thailand from 6am on Thursday (June 11) to 6am on Friday (June 12)

Northern region

• Thunderstorms are forecast for 70% of the area, with heavy to very heavy rain in some places in Mae Hong Son, Chiang Mai, Chiang Rai, Lamphun, Lampang, Phayao, Nan, Phrae, Uttaradit, Kamphaeng Phet, Phichit, Sukhothai, Phitsanulok, Phetchabun and Tak.
• Minimum temperatures are expected at 23–26 degrees Celsius and maximum temperatures at 33–35 degrees Celsius.
• Southwesterly winds are forecast at 10–20km/h.

Northeastern region

• Thunderstorms are forecast for 70% of the area, with heavy to very heavy rain in some places in Loei, Nong Bua Lamphu, Nong Khai, Bueng Kan, Udon Thani, Sakon Nakhon, Nakhon Phanom, Chaiyaphum, Khon Kaen, Kalasin, Mukdahan, Maha Sarakham, Roi Et, Yasothon, Amnat Charoen, Ubon Ratchathani, Nakhon Ratchasima, Buriram, Surin and Sisaket.
• Minimum temperatures are expected at 23–25 degrees Celsius and maximum temperatures at 34–36 degrees Celsius.
• Southwesterly winds are forecast at 10–20km/h.

Central region

• Thunderstorms are forecast for 60% of the area, with heavy rain in some places in Nakhon Sawan, Uthai Thani, Chai Nat, Lopburi, Saraburi, Kanchanaburi, Ratchaburi, Nakhon Pathom and Samut Sakhon.
• Minimum temperatures are expected at 25–26 degrees Celsius and maximum temperatures at 35–36 degrees Celsius.
• Southwesterly winds are forecast at 10–20km/h.

Eastern region

• Thunderstorms are forecast for 60% of the area, with heavy to very heavy rain in some places in Nakhon Nayok, Prachinburi, Sa Kaeo, Rayong, Chanthaburi and Trat.
• Minimum temperatures are expected at 24–28 degrees Celsius and maximum temperatures at 31–35 degrees Celsius.
• Southwesterly winds are forecast at 15–35km/h.
• Waves are expected to be 1–2 metres high, rising above 2 metres in thunderstorm areas.

Southern region, east coast

• Thunderstorms are forecast for 40% of the area, mostly in Prachuap Khiri Khan, Chumphon, Surat Thani, Nakhon Si Thammarat, Phatthalung and Songkhla.
• Minimum temperatures are expected at 23–26 degrees Celsius and maximum temperatures at 34–35 degrees Celsius. Southwesterly winds are forecast at 15–35km/h.
• Waves are expected to be about 1 metre high, rising to 1–2 metres offshore and above 2 metres in thunderstorm areas.

Southern region, west coast

• Thunderstorms are forecast for 80% of the area, with heavy to very heavy rain in some places in Ranong, Phang Nga, Phuket, Krabi, Trang and Satun.
• Minimum temperatures are expected at 23–25 degrees Celsius and maximum temperatures at 30–34 degrees Celsius.
• From Phang Nga northward, southwesterly winds are forecast at 20–35km/h and waves about 2 metres high, rising above 2 metres in thunderstorm areas.
• From Phuket southward, southwesterly winds are forecast at 15–35km/h and waves 1–2 metres high, rising above 2 metres in thunderstorm areas.

Bangkok and its vicinity

• Thunderstorms are forecast for 60% of the area, with heavy rain in some places.
• Minimum temperatures are expected at 26–27 degrees Celsius and maximum temperatures at 34–36 degrees Celsius.
• Southwesterly winds are forecast at 10–25km/h.